drivers/iio/dac/max5821.c - kernel/msm-4.9 - Gitiles

  /*
   * iio/dac/max5821.c
   * Copyright (C) 2014 Philippe Reynes
   *
   * This program is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License version 2 as
   * published by the Free Software Foundation.
   */

 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/i2c.h>
 #include <linux/iio/iio.h>
 #include <linux/regulator/consumer.h>

 #define MAX5821_MAX_DAC_CHANNELS		2

 /* command bytes */
 #define MAX5821_LOAD_DAC_A_IN_REG_B		0x00
 #define MAX5821_LOAD_DAC_B_IN_REG_A		0x10
 #define MAX5821_EXTENDED_COMMAND_MODE		0xf0
 #define MAX5821_READ_DAC_A_COMMAND		0xf1
 #define MAX5821_READ_DAC_B_COMMAND		0xf2

 #define MAX5821_EXTENDED_POWER_UP		0x00
 #define MAX5821_EXTENDED_POWER_DOWN_MODE0	0x01
 #define MAX5821_EXTENDED_POWER_DOWN_MODE1	0x02
 #define MAX5821_EXTENDED_POWER_DOWN_MODE2	0x03
 #define MAX5821_EXTENDED_DAC_A			0x04
 #define MAX5821_EXTENDED_DAC_B			0x08

 enum max5821_device_ids {
 	ID_MAX5821,
 };

 struct max5821_data {
 	struct i2c_client	*client;
 	struct regulator	*vref_reg;
 	unsigned short		vref_mv;
 	bool			powerdown[MAX5821_MAX_DAC_CHANNELS];
 	u8			powerdown_mode[MAX5821_MAX_DAC_CHANNELS];
 	struct mutex		lock;
 };

 static const char * const max5821_powerdown_modes[] = {
 	"three_state",
 	"1kohm_to_gnd",
 	"100kohm_to_gnd",
 };

 enum {
 	MAX5821_THREE_STATE,
 	MAX5821_1KOHM_TO_GND,
 	MAX5821_100KOHM_TO_GND
 };

 static int max5821_get_powerdown_mode(struct iio_dev *indio_dev,
 				      const struct iio_chan_spec *chan)
 {
 	struct max5821_data *st = iio_priv(indio_dev);

 	return st->powerdown_mode[chan->channel];
 }

 static int max5821_set_powerdown_mode(struct iio_dev *indio_dev,
 				      const struct iio_chan_spec *chan,
 				      unsigned int mode)
 {
 	struct max5821_data *st = iio_priv(indio_dev);

 	st->powerdown_mode[chan->channel] = mode;

 	return 0;
 }

 static const struct iio_enum max5821_powerdown_mode_enum = {
 	.items = max5821_powerdown_modes,
 	.num_items = ARRAY_SIZE(max5821_powerdown_modes),
 	.get = max5821_get_powerdown_mode,
 	.set = max5821_set_powerdown_mode,
 };

 static ssize_t max5821_read_dac_powerdown(struct iio_dev *indio_dev,
 					  uintptr_t private,
 					  const struct iio_chan_spec *chan,
 					  char *buf)
 {
 	struct max5821_data *st = iio_priv(indio_dev);

 	return sprintf(buf, "%d\n", st->powerdown[chan->channel]);
 }

 static int max5821_sync_powerdown_mode(struct max5821_data *data,
 				       const struct iio_chan_spec *chan)
 {
 	u8 outbuf[2];

 	outbuf[0] = MAX5821_EXTENDED_COMMAND_MODE;

 	if (chan->channel == 0)
 		outbuf[1] = MAX5821_EXTENDED_DAC_A;
 	else
 		outbuf[1] = MAX5821_EXTENDED_DAC_B;

 	if (data->powerdown[chan->channel])
 		outbuf[1] |= data->powerdown_mode[chan->channel] + 1;
 	else
 		outbuf[1] |= MAX5821_EXTENDED_POWER_UP;

 	return i2c_master_send(data->client, outbuf, 2);
 }

 static ssize_t max5821_write_dac_powerdown(struct iio_dev *indio_dev,
 					   uintptr_t private,
 					   const struct iio_chan_spec *chan,
 					   const char *buf, size_t len)
 {
 	struct max5821_data *data = iio_priv(indio_dev);
 	bool powerdown;
 	int ret;

 	ret = strtobool(buf, &powerdown);
 	if (ret)
 		return ret;

 	data->powerdown[chan->channel] = powerdown;

 	ret = max5821_sync_powerdown_mode(data, chan);
 	if (ret < 0)
 		return ret;

 	return len;
 }

 static const struct iio_chan_spec_ext_info max5821_ext_info[] = {
 	{
 		.name = "powerdown",
 		.read = max5821_read_dac_powerdown,
 		.write = max5821_write_dac_powerdown,
 		.shared = IIO_SEPARATE,
 	},
 	IIO_ENUM("powerdown_mode", IIO_SEPARATE, &max5821_powerdown_mode_enum),
 	IIO_ENUM_AVAILABLE("powerdown_mode", &max5821_powerdown_mode_enum),
 	{ },
 };

 #define MAX5821_CHANNEL(chan) {					\
 	.type = IIO_VOLTAGE,					\
 	.indexed = 1,						\
 	.output = 1,						\
 	.channel = (chan),					\
 	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),		\
 	.info_mask_shared_by_all = BIT(IIO_CHAN_INFO_SCALE),	\
 	.ext_info = max5821_ext_info,				\
 }

 static const struct iio_chan_spec max5821_channels[] = {
 	MAX5821_CHANNEL(0),
 	MAX5821_CHANNEL(1)
 };

 static const u8 max5821_read_dac_command[] = {
 	MAX5821_READ_DAC_A_COMMAND,
 	MAX5821_READ_DAC_B_COMMAND
 };

 static const u8 max5821_load_dac_command[] = {
 	MAX5821_LOAD_DAC_A_IN_REG_B,
 	MAX5821_LOAD_DAC_B_IN_REG_A
 };

 static int max5821_get_value(struct iio_dev *indio_dev,
 			     int *val, int channel)
 {
 	struct max5821_data *data = iio_priv(indio_dev);
 	struct i2c_client *client = data->client;
 	u8 outbuf[1];
 	u8 inbuf[2];
 	int ret;

 	if ((channel != 0) && (channel != 1))
 		return -EINVAL;

 	outbuf[0] = max5821_read_dac_command[channel];

 	mutex_lock(&data->lock);

 	ret = i2c_master_send(client, outbuf, 1);
 	if (ret < 0) {
 		mutex_unlock(&data->lock);
 		return ret;
 	} else if (ret != 1) {
 		mutex_unlock(&data->lock);
 		return -EIO;
 	}

 	ret = i2c_master_recv(client, inbuf, 2);
 	if (ret < 0) {
 		mutex_unlock(&data->lock);
 		return ret;
 	} else if (ret != 2) {
 		mutex_unlock(&data->lock);
 		return -EIO;
 	}

 	mutex_unlock(&data->lock);

 	*val = ((inbuf[0] & 0x0f) << 6) | (inbuf[1] >> 2);

 	return IIO_VAL_INT;
 }

 static int max5821_set_value(struct iio_dev *indio_dev,
 			     int val, int channel)
 {
 	struct max5821_data *data = iio_priv(indio_dev);
 	struct i2c_client *client = data->client;
 	u8 outbuf[2];
 	int ret;

 	if ((val < 0) || (val > 1023))
 		return -EINVAL;

 	if ((channel != 0) && (channel != 1))
 		return -EINVAL;

 	outbuf[0] = max5821_load_dac_command[channel];
 	outbuf[0] |= val >> 6;
 	outbuf[1] = (val & 0x3f) << 2;

 	ret = i2c_master_send(client, outbuf, 2);
 	if (ret < 0)
 		return ret;
 	else if (ret != 2)
 		return -EIO;
 	else
 		return 0;
 }

 static int max5821_read_raw(struct iio_dev *indio_dev,
 			   struct iio_chan_spec const *chan,
 			   int *val, int *val2, long mask)
 {
 	struct max5821_data *data = iio_priv(indio_dev);

 	switch (mask) {
 	case IIO_CHAN_INFO_RAW:
 		return max5821_get_value(indio_dev, val, chan->channel);
 	case IIO_CHAN_INFO_SCALE:
 		*val = data->vref_mv;
 		*val2 = 10;
 		return IIO_VAL_FRACTIONAL_LOG2;
 	default:
 		return -EINVAL;
 	}
 }

 static int max5821_write_raw(struct iio_dev *indio_dev,
 			     struct iio_chan_spec const *chan,
 			     int val, int val2, long mask)
 {
 	if (val2 != 0)
 		return -EINVAL;

 	switch (mask) {
 	case IIO_CHAN_INFO_RAW:
 		return max5821_set_value(indio_dev, val, chan->channel);
 	default:
 		return -EINVAL;
 	}
 }

 #ifdef CONFIG_PM_SLEEP
 static int max5821_suspend(struct device *dev)
 {
 	u8 outbuf[2] = { MAX5821_EXTENDED_COMMAND_MODE,
 			 MAX5821_EXTENDED_DAC_A |
 			 MAX5821_EXTENDED_DAC_B |
 			 MAX5821_EXTENDED_POWER_DOWN_MODE2 };

 	return i2c_master_send(to_i2c_client(dev), outbuf, 2);
 }

 static int max5821_resume(struct device *dev)
 {
 	u8 outbuf[2] = { MAX5821_EXTENDED_COMMAND_MODE,
 			 MAX5821_EXTENDED_DAC_A |
 			 MAX5821_EXTENDED_DAC_B |
 			 MAX5821_EXTENDED_POWER_UP };

 	return i2c_master_send(to_i2c_client(dev), outbuf, 2);
 }

 static SIMPLE_DEV_PM_OPS(max5821_pm_ops, max5821_suspend, max5821_resume);
 #define MAX5821_PM_OPS (&max5821_pm_ops)
 #else
 #define MAX5821_PM_OPS NULL
 #endif /* CONFIG_PM_SLEEP */

 static const struct iio_info max5821_info = {
 	.read_raw = max5821_read_raw,
 	.write_raw = max5821_write_raw,
 	.driver_module = THIS_MODULE,
 };

 static int max5821_probe(struct i2c_client *client,
 			const struct i2c_device_id *id)
 {
 	struct max5821_data *data;
 	struct iio_dev *indio_dev;
 	u32 tmp;
 	int ret;

 	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
 	if (!indio_dev)
 		return -ENOMEM;
 	data = iio_priv(indio_dev);
 	i2c_set_clientdata(client, indio_dev);
 	data->client = client;
 	mutex_init(&data->lock);

 	/* max5821 start in powerdown mode 100Kohm to ground */
 	for (tmp = 0; tmp < MAX5821_MAX_DAC_CHANNELS; tmp++) {
 		data->powerdown[tmp] = true;
 		data->powerdown_mode[tmp] = MAX5821_100KOHM_TO_GND;
 	}

 	data->vref_reg = devm_regulator_get(&client->dev, "vref");
 	if (IS_ERR(data->vref_reg)) {
 		ret = PTR_ERR(data->vref_reg);
 		dev_err(&client->dev,
 			"Failed to get vref regulator: %d\n", ret);
 		goto error_free_reg;
 	}

 	ret = regulator_enable(data->vref_reg);
 	if (ret) {
 		dev_err(&client->dev,
 			"Failed to enable vref regulator: %d\n", ret);
 		goto error_free_reg;
 	}

 	ret = regulator_get_voltage(data->vref_reg);
 	if (ret < 0) {
 		dev_err(&client->dev,
 			"Failed to get voltage on regulator: %d\n", ret);
 		goto error_disable_reg;
 	}

 	data->vref_mv = ret / 1000;

 	indio_dev->name = id->name;
 	indio_dev->dev.parent = &client->dev;
 	indio_dev->num_channels = ARRAY_SIZE(max5821_channels);
 	indio_dev->channels = max5821_channels;
 	indio_dev->modes = INDIO_DIRECT_MODE;
 	indio_dev->info = &max5821_info;

 	return iio_device_register(indio_dev);

 error_disable_reg:
 	regulator_disable(data->vref_reg);

 error_free_reg:

 	return ret;
 }

 static int max5821_remove(struct i2c_client *client)
 {
 	struct iio_dev *indio_dev = i2c_get_clientdata(client);
 	struct max5821_data *data = iio_priv(indio_dev);

 	iio_device_unregister(indio_dev);
 	regulator_disable(data->vref_reg);

 	return 0;
 }

 static const struct i2c_device_id max5821_id[] = {
 	{ "max5821", ID_MAX5821 },
 	{ }
 };
 MODULE_DEVICE_TABLE(i2c, max5821_id);

 static const struct of_device_id max5821_of_match[] = {
 	{ .compatible = "maxim,max5821" },
 	{ }
 };

 static struct i2c_driver max5821_driver = {
 	.driver = {
 		.name	= "max5821",
 		.pm     = MAX5821_PM_OPS,
 		.owner	= THIS_MODULE,
 	},
 	.probe		= max5821_probe,
 	.remove		= max5821_remove,
 	.id_table	= max5821_id,
 };
 module_i2c_driver(max5821_driver);

 MODULE_AUTHOR("Philippe Reynes <tremyfr@yahoo.fr>");
 MODULE_DESCRIPTION("MAX5821 DAC");
 MODULE_LICENSE("GPL v2");
	/*
	* iio/dac/max5821.c
	* Copyright (C) 2014 Philippe Reynes
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License version 2 as
	* published by the Free Software Foundation.
	*/

	#include <linux/kernel.h>
	#include <linux/module.h>
	#include <linux/i2c.h>
	#include <linux/iio/iio.h>
	#include <linux/regulator/consumer.h>

	#define MAX5821_MAX_DAC_CHANNELS 2

	/* command bytes */
	#define MAX5821_LOAD_DAC_A_IN_REG_B 0x00
	#define MAX5821_LOAD_DAC_B_IN_REG_A 0x10
	#define MAX5821_EXTENDED_COMMAND_MODE 0xf0
	#define MAX5821_READ_DAC_A_COMMAND 0xf1
	#define MAX5821_READ_DAC_B_COMMAND 0xf2

	#define MAX5821_EXTENDED_POWER_UP 0x00
	#define MAX5821_EXTENDED_POWER_DOWN_MODE0 0x01
	#define MAX5821_EXTENDED_POWER_DOWN_MODE1 0x02
	#define MAX5821_EXTENDED_POWER_DOWN_MODE2 0x03
	#define MAX5821_EXTENDED_DAC_A 0x04
	#define MAX5821_EXTENDED_DAC_B 0x08

	enum max5821_device_ids {
	ID_MAX5821,
	};

	struct max5821_data {
	struct i2c_client *client;
	struct regulator *vref_reg;
	unsigned short vref_mv;
	bool powerdown[MAX5821_MAX_DAC_CHANNELS];
	u8 powerdown_mode[MAX5821_MAX_DAC_CHANNELS];
	struct mutex lock;
	};

	static const char * const max5821_powerdown_modes[] = {
	"three_state",
	"1kohm_to_gnd",
	"100kohm_to_gnd",
	};

	enum {
	MAX5821_THREE_STATE,
	MAX5821_1KOHM_TO_GND,
	MAX5821_100KOHM_TO_GND
	};

	static int max5821_get_powerdown_mode(struct iio_dev *indio_dev,
	const struct iio_chan_spec *chan)
	{
	struct max5821_data *st = iio_priv(indio_dev);

	return st->powerdown_mode[chan->channel];
	}

	static int max5821_set_powerdown_mode(struct iio_dev *indio_dev,
	const struct iio_chan_spec *chan,
	unsigned int mode)
	{
	struct max5821_data *st = iio_priv(indio_dev);

	st->powerdown_mode[chan->channel] = mode;

	return 0;
	}

	static const struct iio_enum max5821_powerdown_mode_enum = {
	.items = max5821_powerdown_modes,
	.num_items = ARRAY_SIZE(max5821_powerdown_modes),
	.get = max5821_get_powerdown_mode,
	.set = max5821_set_powerdown_mode,
	};

	static ssize_t max5821_read_dac_powerdown(struct iio_dev *indio_dev,
	uintptr_t private,
	const struct iio_chan_spec *chan,
	char *buf)
	{
	struct max5821_data *st = iio_priv(indio_dev);

	return sprintf(buf, "%d\n", st->powerdown[chan->channel]);
	}

	static int max5821_sync_powerdown_mode(struct max5821_data *data,
	const struct iio_chan_spec *chan)
	{
	u8 outbuf[2];

	outbuf[0] = MAX5821_EXTENDED_COMMAND_MODE;

	if (chan->channel == 0)
	outbuf[1] = MAX5821_EXTENDED_DAC_A;
	else
	outbuf[1] = MAX5821_EXTENDED_DAC_B;

	if (data->powerdown[chan->channel])
	outbuf[1] \|= data->powerdown_mode[chan->channel] + 1;
	else
	outbuf[1] \|= MAX5821_EXTENDED_POWER_UP;

	return i2c_master_send(data->client, outbuf, 2);
	}

	static ssize_t max5821_write_dac_powerdown(struct iio_dev *indio_dev,
	uintptr_t private,
	const struct iio_chan_spec *chan,
	const char *buf, size_t len)
	{
	struct max5821_data *data = iio_priv(indio_dev);
	bool powerdown;
	int ret;

	ret = strtobool(buf, &powerdown);
	if (ret)
	return ret;

	data->powerdown[chan->channel] = powerdown;

	ret = max5821_sync_powerdown_mode(data, chan);
	if (ret < 0)
	return ret;

	return len;
	}

	static const struct iio_chan_spec_ext_info max5821_ext_info[] = {
	{
	.name = "powerdown",
	.read = max5821_read_dac_powerdown,
	.write = max5821_write_dac_powerdown,
	.shared = IIO_SEPARATE,
	},
	IIO_ENUM("powerdown_mode", IIO_SEPARATE, &max5821_powerdown_mode_enum),
	IIO_ENUM_AVAILABLE("powerdown_mode", &max5821_powerdown_mode_enum),
	{ },
	};

	#define MAX5821_CHANNEL(chan) { \
	.type = IIO_VOLTAGE, \
	.indexed = 1, \
	.output = 1, \
	.channel = (chan), \
	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
	.info_mask_shared_by_all = BIT(IIO_CHAN_INFO_SCALE), \
	.ext_info = max5821_ext_info, \
	}

	static const struct iio_chan_spec max5821_channels[] = {
	MAX5821_CHANNEL(0),
	MAX5821_CHANNEL(1)
	};

	static const u8 max5821_read_dac_command[] = {
	MAX5821_READ_DAC_A_COMMAND,
	MAX5821_READ_DAC_B_COMMAND
	};

	static const u8 max5821_load_dac_command[] = {
	MAX5821_LOAD_DAC_A_IN_REG_B,
	MAX5821_LOAD_DAC_B_IN_REG_A
	};

	static int max5821_get_value(struct iio_dev *indio_dev,
	int *val, int channel)
	{
	struct max5821_data *data = iio_priv(indio_dev);
	struct i2c_client *client = data->client;
	u8 outbuf[1];
	u8 inbuf[2];
	int ret;

	if ((channel != 0) && (channel != 1))
	return -EINVAL;

	outbuf[0] = max5821_read_dac_command[channel];

	mutex_lock(&data->lock);

	ret = i2c_master_send(client, outbuf, 1);
	if (ret < 0) {
	mutex_unlock(&data->lock);
	return ret;
	} else if (ret != 1) {
	mutex_unlock(&data->lock);
	return -EIO;
	}

	ret = i2c_master_recv(client, inbuf, 2);
	if (ret < 0) {
	mutex_unlock(&data->lock);
	return ret;
	} else if (ret != 2) {
	mutex_unlock(&data->lock);
	return -EIO;
	}

	mutex_unlock(&data->lock);

	*val = ((inbuf[0] & 0x0f) << 6) \| (inbuf[1] >> 2);

	return IIO_VAL_INT;
	}

	static int max5821_set_value(struct iio_dev *indio_dev,
	int val, int channel)
	{
	struct max5821_data *data = iio_priv(indio_dev);
	struct i2c_client *client = data->client;
	u8 outbuf[2];
	int ret;

	if ((val < 0) \|\| (val > 1023))
	return -EINVAL;

	if ((channel != 0) && (channel != 1))
	return -EINVAL;

	outbuf[0] = max5821_load_dac_command[channel];
	outbuf[0] \|= val >> 6;
	outbuf[1] = (val & 0x3f) << 2;

	ret = i2c_master_send(client, outbuf, 2);
	if (ret < 0)
	return ret;
	else if (ret != 2)
	return -EIO;
	else
	return 0;
	}

	static int max5821_read_raw(struct iio_dev *indio_dev,
	struct iio_chan_spec const *chan,
	int val, int val2, long mask)
	{
	struct max5821_data *data = iio_priv(indio_dev);

	switch (mask) {
	case IIO_CHAN_INFO_RAW:
	return max5821_get_value(indio_dev, val, chan->channel);
	case IIO_CHAN_INFO_SCALE:
	*val = data->vref_mv;
	*val2 = 10;
	return IIO_VAL_FRACTIONAL_LOG2;
	default:
	return -EINVAL;
	}
	}

	static int max5821_write_raw(struct iio_dev *indio_dev,
	struct iio_chan_spec const *chan,
	int val, int val2, long mask)
	{
	if (val2 != 0)
	return -EINVAL;

	switch (mask) {
	case IIO_CHAN_INFO_RAW:
	return max5821_set_value(indio_dev, val, chan->channel);
	default:
	return -EINVAL;
	}
	}

	#ifdef CONFIG_PM_SLEEP
	static int max5821_suspend(struct device *dev)
	{
	u8 outbuf[2] = { MAX5821_EXTENDED_COMMAND_MODE,
	MAX5821_EXTENDED_DAC_A \|
	MAX5821_EXTENDED_DAC_B \|
	MAX5821_EXTENDED_POWER_DOWN_MODE2 };

	return i2c_master_send(to_i2c_client(dev), outbuf, 2);
	}

	static int max5821_resume(struct device *dev)
	{
	u8 outbuf[2] = { MAX5821_EXTENDED_COMMAND_MODE,
	MAX5821_EXTENDED_DAC_A \|
	MAX5821_EXTENDED_DAC_B \|
	MAX5821_EXTENDED_POWER_UP };

	return i2c_master_send(to_i2c_client(dev), outbuf, 2);
	}

	static SIMPLE_DEV_PM_OPS(max5821_pm_ops, max5821_suspend, max5821_resume);
	#define MAX5821_PM_OPS (&max5821_pm_ops)
	#else
	#define MAX5821_PM_OPS NULL
	#endif /* CONFIG_PM_SLEEP */

	static const struct iio_info max5821_info = {
	.read_raw = max5821_read_raw,
	.write_raw = max5821_write_raw,
	.driver_module = THIS_MODULE,
	};

	static int max5821_probe(struct i2c_client *client,
	const struct i2c_device_id *id)
	{
	struct max5821_data *data;
	struct iio_dev *indio_dev;
	u32 tmp;
	int ret;

	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
	if (!indio_dev)
	return -ENOMEM;
	data = iio_priv(indio_dev);
	i2c_set_clientdata(client, indio_dev);
	data->client = client;
	mutex_init(&data->lock);

	/* max5821 start in powerdown mode 100Kohm to ground */
	for (tmp = 0; tmp < MAX5821_MAX_DAC_CHANNELS; tmp++) {
	data->powerdown[tmp] = true;
	data->powerdown_mode[tmp] = MAX5821_100KOHM_TO_GND;
	}

	data->vref_reg = devm_regulator_get(&client->dev, "vref");
	if (IS_ERR(data->vref_reg)) {
	ret = PTR_ERR(data->vref_reg);
	dev_err(&client->dev,
	"Failed to get vref regulator: %d\n", ret);
	goto error_free_reg;
	}

	ret = regulator_enable(data->vref_reg);
	if (ret) {
	dev_err(&client->dev,
	"Failed to enable vref regulator: %d\n", ret);
	goto error_free_reg;
	}

	ret = regulator_get_voltage(data->vref_reg);
	if (ret < 0) {
	dev_err(&client->dev,
	"Failed to get voltage on regulator: %d\n", ret);
	goto error_disable_reg;
	}

	data->vref_mv = ret / 1000;

	indio_dev->name = id->name;
	indio_dev->dev.parent = &client->dev;
	indio_dev->num_channels = ARRAY_SIZE(max5821_channels);
	indio_dev->channels = max5821_channels;
	indio_dev->modes = INDIO_DIRECT_MODE;
	indio_dev->info = &max5821_info;

	return iio_device_register(indio_dev);

	error_disable_reg:
	regulator_disable(data->vref_reg);

	error_free_reg:

	return ret;
	}

	static int max5821_remove(struct i2c_client *client)
	{
	struct iio_dev *indio_dev = i2c_get_clientdata(client);
	struct max5821_data *data = iio_priv(indio_dev);

	iio_device_unregister(indio_dev);
	regulator_disable(data->vref_reg);

	return 0;
	}

	static const struct i2c_device_id max5821_id[] = {
	{ "max5821", ID_MAX5821 },
	{ }
	};
	MODULE_DEVICE_TABLE(i2c, max5821_id);

	static const struct of_device_id max5821_of_match[] = {
	{ .compatible = "maxim,max5821" },
	{ }
	};

	static struct i2c_driver max5821_driver = {
	.driver = {
	.name = "max5821",
	.pm = MAX5821_PM_OPS,
	.owner = THIS_MODULE,
	},
	.probe = max5821_probe,
	.remove = max5821_remove,
	.id_table = max5821_id,
	};
	module_i2c_driver(max5821_driver);

	MODULE_AUTHOR("Philippe Reynes <tremyfr@yahoo.fr>");
	MODULE_DESCRIPTION("MAX5821 DAC");
	MODULE_LICENSE("GPL v2");